In the production of plastic conveyors, drive chains and the like, particularly for systems where cleanliness and freedom from lubrication is required (such as in the handling of food products) it is highly desirable to manufacture the moving parts from plastic. However molding of plastic parts generally requires expensive molds which have utility for making only one single part. While mold inserts have been used to change certain features in molded pieces, as far as is known, the molding of sprockets has always required intricately designed molds which constitute a mirror image of the sprocket tooth shape, there being a separate mold required for each different sprocket diameter.